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- ItemAn integrated 3.1-5.1 GHz pulse generator for ultra-wideband wireless localization systems(Göttingen : Copernicus, 2006) Fan, X.; Fischer, G.; Dietrich, B.This paper presents an implementation of an integrated Ultra-wideband (UWB), Binary-Phase Shift Keying (BPSK) Gaussian modulated pulse generator. VCO, multiplier and passive Gaussian filter are the key components. The VCO provides the carrier frequency of 4.1 GHz, the LC Gaussian filter is responsible for the pulse shaping in the baseband. Multiplying the baseband pulse and the VCO frequency shifts the pulse to the desired center frequency. The generated Gaussian pulse ocupppies the frequency range from 3.1 to 5.1 GHz with the center frequency at 4.1 GHz. Simulations and measured results show that this spectrum fulfills the mask for indoor communication systems given by the FCC (Federal Communications Commission, 2002). The total power consumption is 55 mW using a supply voltage of 2.5 V. Circuits are realized using the IHP 0.25 μm SiGe:C BiCMOS technology.
- ItemModelling carbon dynamics from urban land conversion: Fundamental model of city in relation to a local carbon cycle(London : Biomed Central, 2006) Svirejeva-Hopkins, A.; Schellnhuber, H.-J.Background: The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process of urbanization to the Global Carbon Cycle (GCC). Note that, on the contrary to many investigations that have considered direct anthropogenic emission of CO2(urbanized territories produce ca. 96-98% of it), we are interested in more subtle, and up until the present time, weaker processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized". Results: In order to fulfil this task, we first develop a fundamental model of urban space, since the type of land cover within a city makes a difference for a local carbon cycle. Hence, a city is sub-divided by built-up, "green"(parks, etc.) and informal settlements (favelas) fractions. Another aspect is a sub-division of the additional two regions, which makes the total number reaching eight regions, while the UN divides the world by six. Next, the basic model of the local carbon cycle for urbanized territories is built. We consider two processes: carbon emissions as a result of conversion of natural lands caused by urbanization; and the transformation of carbon flows by "urbanized" ecosystems; when carbon, accumulated by urban vegetation, is exported to the neighbouring territories. The total carbon flow in the model depends, in general, on two groups of parameters. The first includes the NPP, and the sum of living biomass and dead organic matter of ecosystems involved in the process of urbanization, and namely them we calculate here, using a new more realistic approach and taking into account the difference in regional cities' evolution. Conclusion: There is also another group of parameters, dealing with the areas of urban territories, and their annual increments. A method of dynamic forecasting of these parameters, based on the statistical regression model, was already suggested; nevertheless we shall further develop a new technique based on one idea to use the gamma-distribution. This will allow us to calculate the total carbon balance and to show how urbanization shifts it. © 2006 Svirejeva-Hopkins and Schellnhuber; licensee BioMed Central Ltd.
- ItemData publication in the open access initiative(London : Ubiquity Press, 2006) Klump, J.; Bertelmann, R.; Brase, J.; Diepenbroek, M.; Grobe, H.; Höck, H.; Lautenschlager, M.; Schindler, U.; Sens, I.; Wächter, J.The 'Berlin Declaration' was published in 2003 as a guideline to policy makers to promote the Internet as a functional instrument for a global scientific knowledge base. Because knowledge is derived from data, the principles of the 'Berlin Declaration ' should apply to data as well. Today, access to scientific data is hampered by structural deficits in the publication process. Data publication needs to offer authors an incentive to publish data through long-term repositories. Data publication also requires an adequate licence model that protects the intellectual property rights of the author while allowing further use of the data by the scientific community.
- ItemAn 8-fold parallel reactor system for combinatorial catalysis research(New York : Hindawi, 2006) Stoll, N.; Allwardt, A.; Dingerdissen, U.; Thurow, K.Increasing economic globalization and mounting time and cost pressure on the development of new raw materials for the chemical industry as well as materials and environmental engineering constantly raise the demands on technologies to be used. Parallelization, miniaturization, and automation are the main concepts involved in increasing the rate of chemical and biological experimentation. Copyright © 2006 Norbert Stoll et al.
- ItemStatistical characteristics of surrogate data based on geophysical measurements(Göttingen : Copernicus, 2006) Venema, V.; Bachner, S.; Rust, H.W.; Simmer, C.In this study, the statistical properties of a range of measurements are compared with those of their surrogate time series. Seven different records are studied, amongst others, historical time series of mean daily temperature, daily rain sums and runoff from two rivers, and cloud measurements. Seven different algorithms are used to generate the surrogate time series. The best-known method is the iterative amplitude adjusted Fourier transform (IAAFT) algorithm, which is able to reproduce the measured distribution as well as the power spectrum. Using this setup, the measurements and their surrogates are compared with respect to their power spectrum, increment distribution, structure functions, annual percentiles and return values. It is found that the surrogates that reproduce the power spectrum and the distribution of the measurements are able to closely match the increment distributions and the structure functions of the measurements, but this often does not hold for surrogates that only mimic the power spectrum of the measurement. However, even the best performing surrogates do not have asymmetric increment distributions, i.e., they cannot reproduce nonlinear dynamical processes that are asymmetric in time. Furthermore, we have found deviations of the structure functions on small scales.
- ItemMulti-parameter uncertainty analysis of a bifurcation point(Göttingen : Copernicus GmbH, 2006) Knopf, B.; Flechsig, M.; Zickfeld, K.Parameter uncertainty analysis of climate models has become a standard approach for model validation and testing their sensitivity. Here we present a novel approach that allows one to estimate the robustness of a bifurcation point in a multi-parameter space. In this study we investigate a box model of the Indian summer monsoon that exhibits a saddle-node bifurcation against those parameters that govern the heat balance of the system. The bifurcation brings about a change from a wet summer monsoon regime to a regime that is characterised by low precipitation. To analyse the robustness of the bifurcation point itself and its location in parameter space, we perform a multi-parameter uncertainty analysis by applying qualitative, Monte Carlo and deterministic methods that are provided by a multi-run simulation environment. Our results show that the occurrence of the bifurcation point is robust over a wide range of parameter values. The position of the bifurcation, however, is found to be sensitive on these specific parameter choices.
- ItemCrystal structure of bis(1,3-bis[{4-methyl-pyridin-2-yl}amido]-1,1,3,3-tetramethyldisiloxane)dichromium dichloride, [(C16H24N4OSi2)CrCl]2(Berlin : de Gruyter, 2006) Irrgang, T.; Spannenberg, A.; Kempe, R.C32H48Cl2Cr2N8O2Si=, monoclinic, P121/n1 (no. 14), a = 12.416(2) Å, b = 13.668(3) Å, c = 13.172(3) Å, β = 113.83(3)°, V= 2044.8 A3, Z = 2, Rgt(F) = 0.052, wRref(F2) = 0.110, T = 200 K. © 2014 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München. All rights reserved.
- ItemDimethylaminomethylene-α-D-xylo-hept-5-ulofuranurononitrile as building block in the synthesis of 'reversed' C-nucleoside analogues(Berlin : de Gruyter, 2006) Hashmi, I.A.; Feist, H.; Michalik, M.; Reinke, H.; Peseke, K.3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-6-(dimethylaminomethylene) -α-D-xylo-hept-5-ulofuranurononitrile (1) was reacted with amidinium salts, S-methylisothiouronium sulfate, and guanidinium chloride, respectively, in the presence of bases to furnish the 4-(3-O-benzyl-1,2-O-isopropylidene- α-D-xylo-tetrofuranos-4-yl)pyrimidine-5-carbonitriles 2 and the 4-(1,2-O-isopropylidene-α-D-glycero-tetr-3-enofuranos-4-yl) pyrimidine-5-carbonitriles 3, respectively. Treatment of 1 with ethyl 5-aminopyrazole-4-carboxylates yielded the ethyl 7-(3-O-benzyl-1,2-O- isopropylidene-α-D-xylo-tetrofuranos-4-yl)-6-cyanopyrazolo[1,5-a] pyrimidine-3-carboxylates 4 and the ethyl 7-amino-6-(3-O-benzyl-1,2-O- isopropylidene-α-D-xylo-pentofuranuronoyl)pyrazolo[1,5-a] pyrimidine-3-carboxylates 5, respectively. Reaction of 1 with 2-benzimidazolylacetonitrile in the presence of sodium methanolate afforded 1-amino-2-(3-O-benzyl-1,2-O-isopropylidene-α-D-xylo-pentofuranuronoyl) benzo[4,5]imidazo[1,2-a]pyridine-4-carbonitrile (6) and 1-amino-2-(3-deoxy-1,2- O-isopropylidene-α-D-glycero-pent-S-enofuranuronoyl)benzo[4,5]imidazo[1, 2-a]pyridine-4-carbonitrile (7). © 2006 Verlag der Zeitschrift für Naturforschung.
- ItemNucleoside analogues from push-pull functionalized branched-chain pyranosides(Berlin : de Gruyter, 2006) Kordian, M.; Feist, H.; Kantlehner, W.; Michalik, M.; Peseke, K.The reaction of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro- hexopyranosid-3-ulose (1) with ethynylmagnesium bromide in tetrahydrofuran and subsequent trimethylsilylation yielded the methyl 4,6-O-benzylidene-2-deoxy-3-C- ethynyl-3-O-trimethylsilyl-α-D-ribo-hexopyranoside (3). Push-pull functionalization of 3 with N,N,N′,N′,N″,N″- hexamethylguanidinium chloride under basic conditions and following deprotection afforded the spiro{2,5-dihydro-3-dimethylamino-furan-2,8'-4',4'a,6',7',8',8'a- hexahydro-6'-methoxy-2'-phenyl-pyrano[3,2-d][1,3]dioxine}-5- ylidenemalononitrile (9). Furthermore, compound 1 reacted with N,N-dimethylformamide dimethylacetal to furnish methyl (E)-4,6-O-benzylidene-2- deoxy-2-dimethylaminomethylene-α-D-erythro-hexopyranosid-3-ulose (10). Treatment of 10 with methylhydrazine and amidines yielded (4S,5aR,8R,9aS)-2,5a, 6,9a-tetrahydro-4-methoxy-2-methyl-8-phenyl-4H-[1,3]dioxino[4',5':5,6]pyrano[4, 3-c]pyrazole (11a) and (2R,4aR,6S,10bS)-4,4a,6,10b-tetrahydro-6-methoxy-2- phenyl[1,3]dioxino[4',5':5,6]pyrano[4,3-d]pyrimidines 12, respectively. © 2006 Verlag der Zeitschrift für Naturforschung.